The silver lining of the election outcome is that the extreme left and center parties have to form a coalition. Even if they manage to formally do that there'll be constant struggle and several such alliances failed across Europe recently.
Macron's interior minister already said he will not support a coalition with the far-left and greens. If that happens he'll be the first to sign a vote of no confidence.
Meanwhile the far-left is organizing a march on the seat of the prime minister in Paris to force Macron to be put in charge of the new government.
For added lulz: some in the socialist German party SPD warned against far-left leader Mélenchon and called him "nationalist, anti-Semitic populist" and "anti-European".
I'm less optimistic. If they hate the right enough to collude with each other to cheat them out of the election then they hate the right enough to put up with each other in a collation government. It might not be coherent or functional but they'll burn the whole thing down before they let someone who gives a shit about native French people into government.
Also my understanding is that the left, crypto left (Macron is a barely disguised leftist himself; his opinion on gaming is no different than a Kotaku blogger) and right are coalitions themselves rather than parties. So Macron can just team up with the leftist parties that he's not in a spat with at the moment. It's not like he disagrees with them ideologically. It's just a dispute over who gets to benefit from the corruption. Macron can easily find some temporary butt buddies if he offers them a sweet enough deal.